Method for sand control in wells



M. H. HARRIS ETAL 3,447,607

METHOD FOR SAND CONTROL IN WELLS `Iune 3, 1969 sheet @f4 Filed March lO, 1967 rmEORs SS w l u n l n l u.' 'l 4 nu l. .f\ 2

June 3, 1969 M. H. HARRIS ETAL 3,447,607

METHOD FOR SAND CONTROL IN WELLS Sheet Filed March l0, 1967 INVENTORS. MA'//V #ARR/5 JAMES l/V. JEA/N/NGS FRANC/5' M SAI/7h June 3, 1969 M, H, HARRlS ETAL 3,447,607

METHOD FOR SAND CONTROL IN WELLS Filed MarOh lO, 1967 Shee(l j June 3, 1969 M. H. HARRIS ETAL 3,447,607

METHOD FOR SAND CONTROL IN WELLS Filed March lo, 1967 sheet 4 of 4 CAR I N VE NTORS. MART/N H. HRR/S JAA/E5 M JEN/V//VS FRANC/5 M SAI/TH United States Patent O U.S. Cl. 166 278 2 Claims ABSTRACT OF THE DISCLOSURE A special tool is lowered into a well and two vertically spaced perforations are created. A volume of formation outside the casing is washed out between the perforations, the tool is rotated, and filter plugs are hydraulically pushed into the perforations and locked into place. The tool is removed and the well is produced to pack a zone of high permeability sand around the filter plugs.

When a well is in contact with a hydrocarbon bearing layer in the earth which is composed in large part of loose sand, there are a number of production problems which must be solved. The usual procedure of producing from such a layer is to set a casing in the well which is secured in place by means of a cement sheath between the outside of the casing and the formation. The casing and the cement sheath are then perforated to provide openings through which the oil and gas iiows into the inside of the casing and up to the surface. If no control means are provided, the loose sand will fiow through the perforations and either block them up or fill the inside of the casing, or otherwise interfere with or stop production.

Various kinds of filter spikes or plugs may be inserted through the perforations to prevent the entry of sand and the like into the inside of the casing. However, this tends to create a zone of low permeability around the spike due to compaction of the formation, crushed sand and the like immediately around the spike.

The present invention comprises a method which comprises the use of a special tool which when lowered into the Well down to the cased and cemented producing zone produces a pair of vertically spaced perforations, creates a hollow cavity or void in the formation between the per` forations, inserts filter spikes into the perforations and into the void in the formation created previously, and then creates a zone of high permeability around the filter spikes by producing the well. The production of the well permits a small amount of small sand particles to pass through the filter spike. These smaller particles, if they were permitted to pack around the filter spike would foul it. During a short production time, larger sand particles will bridge around the openings in the filter spike. The larger particles create relatively large spaces between them, which create the zone of high permeability. The smaller particles will bridge on the larger particles as the pack builds outwardly from the spike into the void.

The invention solves another problem present in prior methods and apparatuses concerning the use of filter spikes. The problem involves the proper alignment of the filter spike before it is inserted into the perforation. Misalignment of the spike and perforation when inserting will cause damage to either or both of the spike and the perforation which will result in the failure of the spike to seal properly in the perforation causing leakage around the spike into the casing. The present invention solves this problem by providing a tool which does not move axially in the well between the steps of perforating and inserting of the filter plugs, so that proper alignment of the plugs and openings is assured.

Patented June 3, 1969 ICC In the accompanying drawing forming a part of this disclosure: FIG. l is a cross-sectional View through a part of a well in the earth with the tool of the invention in place for the first step in the method; FIGS. v2, 3, 4 and 5 are cross-sectional views taken on lines 2 2, 3 3, 4 4, and 5 5 respectively of FIG. l; FIGS. 6, 7, and 8 are figures similar to FIG. l showing succeeding steps in method; FIG. 9 is a view of a filter spike; and FIG. l0 is a partial view of the built up pack on the filter spike.

Referring now in detail to the drawing, 10 designates a well traversing an oil bearing layer 12. Well 10 has been completed through layer 12 by means of a casing 14 which is secured in position by a cement sheath 16 between the casing and the formation.

A tool 18 embodying the invention is located in well 10 adjacent layer 12. Tool 18 is supported on the lower end of a length of well tubing 20 which has its lower end specially fabricated for cooperation with tool 18, and which may be joined at its upper end to the usual well tubing in any conventional manner, not shown. In spaced relation above its lower end, tubing 20 is provided with a pair of opposed ears 22 which are axially and slidably received within a pair of blind slots 24 formed in the upper neck 26 of tool 18. Thus, tubing 20 is constrained to axial motion with respect to neck 26 of tool 18 with limits defined by the ends of blind slots 24. The interaction of ears 22 and slots 24 permits rotation of tubing 20 to be transmitted to the remainder of tool 18 by neck 26, for a reason explained below.

The lower end of tubing 20 is sealed shut by means of a bottom plate portion 28. Sealing means 30, such as O rings, slidably seal the interface between the outside of the lower end of tubing 20 and the inside of neck 26. Tool 18 comprises a main body portion 32 formed with a chamber 34 spaced below neck 26. Bottom plate 28 is slidably received within chamber 34 and is constrained to motion within said chamber by interaction of the upper face of bottom plate 28 and the lower end of neck 26. A pair of electrical wires 3S extend through the length of tubing 20 from the surface, and terminate in a pair of plugs 35a which are sealed into bottom plate 28 by any suitable sealing means 35b. Bottom plate 28 is formed with a radial opening 36. A pair of O rings 38 gird bottom plate 28 above and below opening 36 to form a fluid tight seal between said opening and the openings with which opening 36 communicates.

Body portion 32 is formed with an opening 40 and an opening 42 spaced below opening 40. As can be seen from comparison of FIGS. l and 6, opening 36 communicates with opening 40 in the upper position of bottom plate 28 in chamber 34, and communicates with opening 42 in the lower position thereof.

Means are provided to seal tool 18 at a selected position axially in the well. To this end, a plurality of packer ring assemblies 44 are provided in body portion 32 of tool 18. All the packer ring assemblies are similar, and each comprises a metal ring 46 which is rotatably and sealably received within a suitable opening 48 formed in body portion 32. Each ring 46 is formed with a fluid receiving pocket S0 on its outer cylindrical face which encircles the ring. An inliatable packer 52, of any suitable type, is joined to the edges of the outer face of each ring so that a pressurized fluid supplied to pocket 50 will force packer 52 into contact with casing 14 to hold tool 18 in position. Means are provided to supply a pressurized fluid to pockets 50, and to hold the packers 52 under pressure until the entire well treatment is completed. To this end, each ring 46 is provided with an axial passageway 54 including a connecting passageway to pocket 50. The bot- 3 tom passageway dead ends at its pocket 50. The uppermost passageway 54 is in communication with the lower end of passageway 40. Body portion 32 is formed with a plurality of passageways 56 which interconnect the passageways 54 of the packer rings.

The tool is set in the casing as follows: It is lowered on tubing to the desired level, and pressurized fluid, which may -be oil, water, or other suitable fluid is supplied down the tubing and passes through passageways 36, 40, S4 and 56 to fill the pockets 50 and inflate the packers. Tubing 20 is then dropped within neck 26, but the packers remain inated because of sealing means 38.

Means are provided to permit rotation of body portion 32 with respect to packer ring assemblies 44, which are fixed with respect to the casing, and to maintain commimication between the axial passageways described above, and the second set of axial passageways to be described hereinafter. To this end, each interface between a radially disposed face of a packer ring 46 and the opposed radially disposed face of an opening 48 is provided with suitable sealing means such as O rings, which dene discrete annular spaces between themselves.

Means are provided to create two vertically spaced openings through the casing 14, cement sheath 16, and into formation 12. To this end, body portion 32 is formed with a lower perforator receiving chamber 60 and an upper perforator receiving chamber 62. Chamber 60 iS spaced between the lower two packer assemblies 44 and the upper chamber 62 is spaced between the upper two packer assemblies 44. Mounted in each chamber 60 and 62 is a shaped charged perforator 64 of usual construction. Means are provided to fire charges 64 from the surface. Each charge 64 has a pair of detonating wires 66 which are connected to wires via plugs 35a. Tool body 32 is formed With suitable small openings 68 through which wires 66 pass and which terminate in a plug 70 which cooperates with plugs 35a when the well tubing 20 is dropped to the lower position,to set the circuit up for firing from the surface. Suitable iiuid tight seals 72 are at the ends of openings 68 to permit passage of the wires therethrough. Upper perforator chamber 62 communicates with a passageway 74, which passes through the uppermost packer ring 46 and up to the top of body portion 32. The upper end of passageway 74 is sealed by a blow-out disc 76. When perforator 64 fires, the pressure of the explosion will destroy blow-out disc 76, opening passageway 74 for a reason appearing below. Chamber 60 communicates with a passageway 78, which is spaced below the plane of chamber 60, and which extends across the tool. Means are provided to join opening 36 to the opposite end of passageway 78. To this end, packer rings 46 are provided with axial passageways 80, each spaced radially inwardly of the passageway 54 in the ring. The passageways 80 are interconnected to each other and to passageway 78 and opening 36- by means of passageways 82 formed in body portion 32 and spaced inwardly of the passageways 56.

Means are provided to wash out the formation between the two perforations 84 created by perforators 64. Upon firing, blow-out disc 76 is removed, the charges and their lead wires forward of the seals 72 are consumed, and a continuous tiow passage is created for liuid to perform said washing. Oil, water, or any other suitable iiuid may be used for washing. The liow path for the washing fluid is as follows: From suitable pumps on the surface down the annulus between tubing 22 and casing 14, into passageway 74, through upper chamber 62, through upper perforator 84, through the formation, into lower perforation 84, through chamber 60, passageway 78, passageways 82 and 80, opening 36, and back up to the surface through the inside of tubing 20. The washing continues until a void 86 of suiiicient size is created. The operator is able to tell when void 86 is sufficiently large by the volume of formation material collected at the surface.

After void 86 is created, means are provided to insert Cil iilter plugs, of any suitable type, through perforations 84 and into void 86. To this end, body portion 32 is provided with a pair of lilter plug receiving chambers 88 disposed at right angles to passageway 78 and in the planes of chambers and 62, respectively. Body portion 32 is provided with a passageway 90, which is at the same radial distance from the center of rotation of the tool as the passageways and 82, and which interconnects the ends of chambers 88. The tubing 20 and the body portion 32 has been turned 90 to the right or in the clockwise direction looking down on the tool from above with respect to the packers in FIG. 8. The packer assemblies 44 remain stationary throughout the entire operation, and the plane through the well on which the cross-sectional View of FIG. 8 is taken is the same as that shown in FIG. l. A passage 92 interconnects the rear end of the -lower chamber 88 with the underside of the lowermost of the middle two packer ring assemblies 44. A passageway 94 interconnects the upper two packer assemblies with the rear end of the upper chamber 88. The upper end of the passageway 80 in the uppermost packer ring is maintained in communication with opening 42 by means of an arcuate cavity 96 formed in the upper radial face of opening 48 in facing relation to the upper packer ring 46. Thus, cavity 96 communicates opening 42 with passageway 94.

Referring to FIG. 5, the filter spike 98 is shown seated in body 32 within its chamber 88. The cavity 96, which is arcuate and extends for serves the purpose of communicating opening 42 with passageway 80 after the tool is turned to the position of FIG. 8. The filter plugs 98 are expelled from the cavities 88 and into perforations 84 by the application of pressurized fluid on passageways 90 and 94, and cavity 96 as described above and as shown in FIG. 8.

As shown in FIG. 4, the system of passageways which supplies pressurized uid behind the packers 52 remains in communication with opening 40 even after the tool is turned, by means of cavities 102, see FIG. 4, which are arcuate for 90. A cavity 102 is provided in the tool body between each interface of the tool and a packer ring. By means of these cavities 102, the pressure behind the inatable packers can be released at the end of the operation as will appear below.

Referring now to FIG. 9, one filter spike or plug 98 is shown in detail. It is to be understood that the spike shown in FIG. 9 is by way of example only, and that any other suitable iilter plug could be provided. Filter spike 98 comprises a hollow plug body 104 which may be tapered, and which is provided with a plurality of lter slots 106 which communicate the outside of the plug with the chamber within the plug. The width of slots 106 is determined by the average grain size of the sand involved. As required, because of the nature of the sand, a plurality of openings of other shape or a plurality of short aligned slots could be provided in place of the slots 106 shown. The body 104 may be made of ferrous or nonferrous metals, inert plastics such as nylon, Tefion, or the like, or combinations of these materials. The rear end of body 104 is provided with a threaded connecting portion 108.

Mounted on threads 108 is a cap member 110 provided with a threaded portion 112 which mates with threads 108 to join the cap to the body. The outside of cap 110 is formed into a plurality of staggered teeth 114, as shown in FIG. 8, which wedge against the edges of perforations 84 in casing 14 to form a duid-tight seal. A piston member 116, which ts snugly within chamber 88 and permits the action of the pressurized uid in the charge to expel the filter spike, is joined to the rear end of member 110 by means of a'shear pin 118. When the spikes are in place, the tool is removed from the well and the shear pins break off. This is accomplished by raising drill pipe 20 with respect to neck 26 to bring opening 36 into registry with opening 40, releasing the pressure in the drill pipe at the surface, which allows the pressurized fluid in pockets 50 to escape through the drill pipe, thus deflating packers 52. Continued upward pull on tubing 20 will break off the shear pins 118 leaving the lter plugs 98 in place.

The well is then produced, and, as shown in FIG. 10, a zone of high permeability is created immediately around the filter plugs. This zone of high permeability is created because only larger sand particles bridge on the filter slots or openings in the plug at first, and only thereafter do the smaller particles bridge on the larger particles.

The advantages of the invention include the high degree of control of perforating efiiciency, and accuracy of placement of the filter plugs in the perforations. Also, damage from cement, mud, crushed sand, and debris from the explosion of the charges, is eliminated because of the washing and circulating through the perforations. Since the well is produced when the filter plug is in a void, the problem of crushed sand clogging the filter plug is completely eliminated. The selective control of the size and type of openings in the filter plug permits the use of a filter specially designed for each type of sand encountered.

While the invention has been described in detail above, it is to be understood that this detailed description is by way of example only, and the protection granted is to be limited only Within the spirit of the invention and the scope of the following claims.

We claim:

1. A method of sand control in a cased well comprising the steps of creating a pair of vertically spaced perforations through the casing and into the formation, circulating fiuid through the perforations to create a void between the perforations in the formation, inserting a filter spike through each of the perforations and into said void space by applying hydraulic pressure behind each of said lter spikes, and producing the well through said perforations to form a zone of high permeability immediately surrounding said filter spikes.

2. The method of claim 1, wherein said perforations are created -by electrically detonating shaped explosive charges.

References Cited UNITED STATES PATENTS 2,482,913 9/1949 lobe 166-55.1 2,540,123 2/1951 Kinley 166-55.1 2,775,303 12/ 1956 Abendroth et al 166-15 3,347,314 10/1967 Schuster 166-35 X 3,367,420 2/1968 Jennings et al. 166--15 X CHARLES E. OCONNELL, Primary Examiner. I. A. CALVERT, Assistant Examiner.

U.S. Cl. X.R. 166-35, 55.1, 100 

